To extend our findings that neurophysins may serve as tumor markers in as many as 60% of patients with samll cell tumors, to the care of these patients. Patients who have plasma levels of one or both neurophysins elevated before commencement of therapy will be monitored by RIAs at each regular clinic session. We will attempt to push therapy to the point where no tumor is detectable by RIA for neurophysins. To begin pulse labeling studies using a tumor cell line that actively produces VP-HNP. This will include measurements of the rates of incorporation of labeled amino acids into products that are precipitated by our antisera specific for VP-HNP and vasopressin. To determine if the proteolytic enzyme found by us in neurosecretory granules of hypothalamic neurons of rats is also a product of tumor cells that manufacture neurophysins and hormones. To measure the daily urinary excretion of vasopressin, oxytocin, and vasotocin in patients with small cell carcinoma of the lung. To measure the clearance rates of immunoprecipitable (125I)-human neurophysins from the circulation of rats.